This invention relates to an improvement in audio and video equipment generally, and in particular to an improved knob adapted to be mounted on an operating member, such as an on/off switch or a volume control, to be pushed, depressed, or rotated from the front side of a panel for operation. The invention also relates to an improved stem-mounted knob, which is mounted on a stem of an operating member, such as an on/off switch or a volume control, and having an illumination device provided thereon to provide bright indication of a mark on the front end face of the knob.
In a conventional knob device of this type, an escutcheon 2 is formed on the back side of a front panel 1, as shown in FIGS. 11 and 12. A push button 5, mounted on a stem 4 which is slidable back and forth relative to an operating member 3, such as an on/off switch or a volume control, is slidably received in the escutcheon 2, with its front end projecting outwardly from the front face of the front panel 1.
The push button 5 is depressed from the front side of front panel 1 to operate the operating member 3. By depressing the push button 5 again, the push button 5 is returned so as to project from the front face of the front panel 1, so that the operating member 3 also is returned to its initial condition.
In such a knob device, if an operator of the device feels play or backlash when the push button 5 is depressed, the operator may get the impression that the equipment is of low quality, and may have a disagreeable feeling toward the operation.
If play between the operating member 3 and its stem 4 and play between the push button 5 and the escutcheon 2 both are eliminated, an improper operation, such as an improper returning movement of the push button 5, would be encountered with even a slight error in assembly.
For this reason, conventionally, only one of the occurrences of play present respectively between the operating member 3 and the stem 4 and between the push button 5 and the escutcheon 2 has been eliminated. The other occurrence play is left unchanged.
However, in this case, the method of reducing the play between the push button 5 and the escutcheon 2 is limited. Therefore, depending on the assembly accuracy, the push button 5 may not return properly, and the push button 5 may impinge on the escutcheon 2 because of vibration, thereby producing noise.
Further, the reduction of the play between the operating member 3 and the stem 4 causes a drawback in that the impression of high quality is lost because the gap between the escutcheon 2 and the push button 5 can be viewed from the front side.
Another problem with the conventional knob device is shown in FIG. 13, in which reference numerals are used similar to those used in FIGS. 11 and 12 to denote like elements. A conventional knob incorporating an illumination device of this type has a volume element 3 of the pop-up type which is turned on once it is depressed and is returned to its initial position (turned off) when depressed again. A knob made of a light-transmitting resin is mounted on the front of a stem 4 of the volume element.
White paint is coated on at least the f end face of the knob 5, and then a non-light-transmitting for example, black paint, is coated on the front end so as to provide a mark 5a', such as a character or a figure, as a mortise.
The knob 5 is projected outwardly the front face of the panel 1 so that the knob 5 can be pushed, and in the same manner as described above, a mark 1a', such as a character or a figure, also is provided on the front of the panel 1 either above or below a hole 1b' thereof through which the knob 5 is passed.
A light-guiding member 8 made of light-transmitting resin is mounted on the rear face of the panel 1 facing away from the mark 1a', the light-guiding member a projection 8a projecting so as to face the rear end of knob 5.
With this construction, a light ray a light source (not shown) such as a lamp is guided b light-guiding member 8 to the mark 1a' on the panel 1 to it. Also, the light ray from the projection 8a of the light-guiding member 8 brightens the rear end of the knob 5, and this light transmits through the knob 5 to brighten the mark 5a'.
In such a knob with an illumination device, if a gap between the knob 5 and the hole 1b' through which the knob 5 passes is too small, the knob 5 contacts the edge of this hole so that the frictional resistance to the movement of the knob 5 is increased, possibly causing an improper returning movement of the knob 5.
For this reason, the gap is designed- to be relatively large, and as a result leaking light emitted from the light-guiding member 8 toward the peripheral surface of the knob 5 can be viewed through this gap, which results in degrading of equipment design, and thus providing an impression of low quality.
In view of the foregoing, it is one object of the invention to provide a knob device in which it is unnecessary to eliminate the play present respectively between the operating member and its stem and between the push button and the escutcheon. With the present invention, even when there is a certain degree of variation in assembly accuracy, the operator does not feel the play or backlash, and there is no risk of improper operation.
It is another object of the present invention to prevent leakage of light applied to the outer periphery of the knob. As a result, even if the gap between the knob and the knob-passing hole in the panel is increased, the light will not leak out, thereby ensuring an impression that the equipment is of high quality.